This invention relates to an optical guidance system for remotely controlled, self-propelled vehicles. Vehicles of the type described in this application have many different uses such as for carrying loads, pallets and fixtures, particularly in a manufacturing or warehouse facility.
However, vehicles of the general type described in this application can have other uses such as conveyors in automobile assembly plants and as farm equipment, lawn mowers, sweepers and other types of utility vehicles. Prior art vehicles of this type are generally operated on a fixed track or follow a wire embedded in the floor. The invention described in this application is intended to provide greater flexibility and lower cost in the use of such vehicles, thereby expanding their range of use.
The main problem with known types of automatically guided vehicles is the necessity of using a fixed track or a wire guidance system. For many application, these types are ideal. However, these systems must be installed on or in the floor and, once installed, are not readily moveable. Therefore, such systems are generally suitable where it is known that the vehicle will operate only on a certain pattern and that there will be no need to vary the route that the vehicle will take. In environments where it is necessary to vary the path taken by a vehicle from time to time, manually operated vehicles have been required.
Systems which are referred to as "optical guidance systems" are known in the art. One type of optical system relies on an optical effect called "moire" which uses closely spaced-apart gratings to produce a pattern which is visible to, for example, the pilot of an airplane. The pilot responds to the pattern created in the gratings to keep the airplane on a center line until a given point is reached. This type of technology should be carefully distinguished from that disclosed in this application since it is not automatic in any sense and simply provides a visual reference point and certain steering and control information to an individual who then responds accordingly.
Another type of guidance system is disclosed in the Burgener et al. U.S. Pat. No. 4,236,255. Burgener discloses a moveable rack entry vehicle which rolls along a railroad-like track and stores and retrieves goods from a plurality of storage areas. The particular storage area to be accessed by the vehicle is determined by an universal asynchronous receiver-transmitter, one of which is located on the vehicle and one of which is located at a reference station positioned at one end of the track on which the vehicle rides. Information identifying to the vehicle the area to be accessed is transmitted to the vehicle by optical communication in serial form.
Yet another type of guidance system is disclosed in U.S. Pat. Nos. 4,309,758 and 4,328,545, both to Halsall et al. These patents disclose an unmanned vehicle which is guided toward a pre-determined destination by geometrical computation of light signals received by at least three omni-directional detectors positioned on the vehicle. An on-board computer performs trigonometric computations based upon information fed to it by the three light signal detectors.
In the present invention which is described below in several embodiments, a single light source is used as an aiming point by the vehicle. The light source is detected by a camera lens and the vehicle is maneuvered according to the position of the light within the field of view of the lens. Since no wires or tracks need be attached to the floor, the light need only be moved to a desired location and the controlling computer re-programmed accordingly to make the vehicle follow any pre-determined path. By arranging a plurality of lights in serial form as desired, the vehicle can be programmed to follow a circuitous, easily changeable path.